Where the shins and calves are mottled with various bruises, nicks, and scrapes due to bicycle pedals gone awry. This can happen on any type of bicycle where the user is sloppy about getting their feet situated on the pedals. A special instance might be trying to get one's feet back on spinning fixie pedals.

I've got a bad case of bicycle legs after last night's critical mass so I probably shouldn't wear a skirt to church tomorrow.